Help with TT system & survey

Johnny-G · Sep 28, 2012

Being a high flying city type I've never actually worked on a TT system before so would like some advice on one please

A customer has bought a Grade II listed 'house' and would like me to carry out the recs & rems listed on a survey they had done and I'm not sure on a couple of points, I haven't been to see it yet.

"The fitted earth leakage circuit breaker is of an age and type that is no longer used in the industrial which, also since the 1990s recommended their replacement therefore we advise the distribution board should be replace with a modern counterpart containing RCD protection to the final sub-circuits for the entire installation." - I'm going to remove the ELCB and replace the rewireable board, there is apparently a new RCD unit supplying the garage & what sounds like an RCD spur for the boiler, will these need replacing if I'm fitting a new board?

"The Property is reliant on Earth buried rod system for dissipating Earth fault currents, the main house rod should be tested and an allowance made for its replacement." - So do a Ze & find rod & check it's physical condition?

"A separate earth buried rod must be installed to serve the Garage block." - Why does it need one?

"Supplementary and cross Earth bonding should be increased to exposed extraneous metal parts particular to incoming Services i.e. Water, Oil (Within the Garage) and in the area of the Boiler / cylinder, Tanks etc." - Will this be needed if all circuits have additional RCD protection?

There are a lot of single socket outlets mounted on the skirtings apparently, can these be changed to doubles if requested?

I'm sure I'll have more questions, thanks for any help

Deleted member 9648 · Sep 28, 2012

Johnny-G said:
Being a high flying city type I've never actually worked on a TT system before so would like some advice on one please
A customer has bought a Grade II listed 'house' and would like me to carry out the recs & rems listed on a survey they had done and I'm not sure on a couple of points, I haven't been to see it yet.

"The fitted earth leakage circuit breaker is of an age and type that is no longer used in the industrial which, also since the 1990s recommended their replacement therefore we advise the distribution board should be replace with a modern counterpart containing RCD protection to the final sub-circuits for the entire installation." - I'm going to remove the ELCB and replace the rewireable board, there is apparently a new RCD unit supplying the garage & what sounds like an RCD spur for the boiler, will these need replacing if I'm fitting a new board?.....Ideally fit an insulated CU with an S type 100ma main switch and RCBO's to all circuits.....replace the RCD in the garage board for a DP main switch and the FCU for a non RCD type...other combinations are possible but that would be my preferred way.

"The Property is reliant on Earth buried rod system for dissipating Earth fault currents, the main house rod should be tested and an allowance made for its replacement." - So do a Ze & find rod & check it's physical condition?..Yep....include mechanical protection of the cable as well...and take into account ground conditions at time of inspection with a view to future life and stability....Ra/Ze of <200 ohms complies,but many prefer much lower readings,your call on that one.

"A separate earth buried rod must be installed to serve the Garage block." - Why does it need one? Crap....another myth....although a separate rod linked to the main rod will improve Ra if you consider it necessary.

"Supplementary and cross Earth bonding should be increased to exposed extraneous metal parts particular to incoming Services i.e. Water, Oil (Within the Garage) and in the area of the Boiler / cylinder, Tanks etc." - Will this be needed if all circuits have additional RCD protection?Main bonding is required to incoming extraneous conductive parts irrespective of RCD protection...not supplementary...this muppet is talking out of his rectum...supplementary may only be required in special locations as defined in section 7.
There is no such thing as cross bonding.

There are a lot of single socket outlets mounted on the skirtings apparently, can these be changed to doubles if requested? Yes....as long as circuit arrangements permit

I'm sure I'll have more questions, thanks for any help

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